Conventionally, for most of current electronic devices such as computers and mobile phones, private data (for example, an account name and a payment password of a user account) in a physical memory of an electronic device lacks protection. The private data and common data are both managed by a memory management unit without distinction. An operating system can access the private data in the physical memory based on an address mapping relationship established by the memory management unit under any circumstances. As a result, a hacker may attack the operating system by using a malicious program or a virus to gain an access permit to the operating system, and may freely access the private data in the electronic device. Therefore, the privacy security of a user can be seriously threatened.